Crystal Oscillator - Espressif Systems ESP8266 Series Hardware Design Manuallines

"
GPIO5
SD_DATA_1
SD_DATA_0
SD_CLK
SD_CMD
SD_DATA_3
SD_DATA_2
VDDPST
"

1.4.4. Crystal Oscillator

ESP8266EX can support 40 MHz, 26 MHz and 24 MHz crystal oscillators. The accuracy of
crystal oscillators should be ± 10 PPM, and the operating temperature range should be
between -20°C and 85°C.
Please select the right type of crystal oscillator that is used in the ESP Flash Download Tool.
In circuit design, capacitors C1 and C2, which are connected to the ground are added to
the input and output terminals of the crystal oscillator respectively. The values of the two
capacitors can be flexible, ranging from 6 pF to 22 pF. However, the specific capacitive
values of C1 and C2 depend on further testing of and adjustment to the overall
performance of the whole circuit. The crystal precision should be ±10 PPM.
⚠ Notice:
Defects in the craftsmanship of the crystal oscillators (for example, high frequency deviation and unstable
working temperature) may lead to the malfunction of ESP8266EX, resulting in the decrease of overall
performance.
Espressif
24 GPIO5
23 SDI/SD1
22 SDO/SD0
21
R3 200R SCK/CLK
20 SCS/CMD
19 SWP/SD3
18 SHD/SD2
17
U2
Figure 1-6. ESP8266EX Flash
29
VDDD
28
XTAL_IN
27
XTAL_OUT
26
U0TXD
25
U0RXD
"
Figure 1-7. ESP8266EX Crystal Oscillator
SCS/CMD 1
/CS
6
SCK/CLK
CLK
SHD/SD2 7
/HOLD
FLASH
1
XIN GND
2
GND XOUT
" /30 9
1. ESP8266EX
VDD33
5 SDI/SD1
DI
2
SDO/SD0
DO
3 SWP/SD3
/WP
U3
GND
4
3
2018.12